HOW ANIMALS SEE THE WORLD

The animal kingdom is filled with unique and complex visual perspectives as animals have adapted their vision to survive in their specific habitat. Good eyes for one may not be so good for another. Some animals’ vision is highly tuned to their environments of the air or sea, while others supplement their poor vision with their better senses. Senses such as ultraviolet vision, extra colour receptors, and echolocation (location of objects by reflected sound ) may be hard for humans to imagine, yet are part of the everyday life of hundreds of species of animals.

Man’s best friend

The dog’s eyesight performs best in low light, as during daylight hours, their vision is a somewhat washed out due to their nearsightedness, as well as their lack of true colour vision. Contrary to popular opinion, dogs do not see in black and white; rather they see mainly violet, blue, yellow and shades of grey but are unable to see red and green. What they lack in colour vision, they make up for in their acute sense of smell.

Feline vision

Similar to dogs, cats can see shades of blue and green and are very nearsighted, struggling with objects in the distance.

They are unable to see fine detail or rich colour but have a superior ability to see in the dark.

Cats have slightly better peripheral vision than humans, allowing them to see prey and predators around them.

From the goldfish bowl

Goldfish are designed to see things extremely close-up. They can see almost a full 360 degrees around them, seeing the full fishbowl in one view; however, it would be very blurry and a great challenge to distinguish detail.

Studies show that goldfish are incredibly receptive to refractions of light, which is how they navigate when swimming as the light reveals where objects and other animals are.

Horror movie eyes

In the movies, flies are often depicted as having honeycomb-shaped vision made up of small hexagonal views, but in reality, it’s far more blurry, almost pixelated, as they have an extremely poor viewing distance.

They can however see a full 360 degrees, which isn’t much use unless they are extremely close to their subject.

Despite this, flies have the fastest visual responses out of all animals, which is why they’re so good at getting away from threats.

Best vision in the animal kingdom

Eagles and other birds of prey are the kings of the animal kingdom when it comes to visual acuity. Whereas the human standard for perfect vision is 20/20, the eagle has the visual acuity of 20/5, making it four times stronger than ours.

With the sharpest distance vision of all creatures, eagles are able to focus in on small prey from up to 3 miles away.

Their cornea has the ability to change shape to focus more clearly.

In addition, they have near panoramic vision, can distinguish many more colours and more brilliantly than humans, and can see UV light.

The most efficient hunter on the planet

The most efficient hunter on the planet is not the lion or shark, but the dragonfly, whose success rate is attributed to its eyesight. It is impossible for humans to see what the dragonfly sees, as its world looks very different from the human world.

Dragonflies have 30,000 compound eyes, which consist of a number of smaller visual units. These units present the dragonfly with one picture, not 30,000 little ones. The dragonfly eyes wrap almost all around its head, allowing it to see in all directions at once without moving its head.

The colours humans see are detected by 3 colour photoreceptors: red, blue, and green. Most species of dragonflies have up to 30 colour photoreceptors, which means they are able to see colours humans cannot even imagine. Dragonflies are able to see ultraviolet light and can also see through a polarising filter, allowing them to view prey that may be hiding underwater.

Seeing with sound

Dolphins have reasonably good eyesight underwater as their eyes are located on either side of their head, giving them a wide range of vision.

It is still relatively unknown how detailed dolphin vision is, but dolphins navigate and find their food via echolocation or sonar, sending out sound waves and listening to the changed sound waves bouncing back.

Echolocation is believed to give the dolphin a 3–D picture.

When combined with regular sight, dolphins can determine shape, size, and the internal structure of objects near them.

Best Underwater Vision

Shark eyes are dense with retinal rods, which allows them to see well in dark and murky waters. In addition, their eyes contain a layer of mirrored crystal tissue which reflects light back into the retina, amplifying the amount of available light in their underwater habitat. They have a clear eyelid, which helps them see while simultaneously protecting their eyes.

Added to that, they can detect electromagnetic fields emitted when animals move, allowing them to see prey hiding in the sand as well as locate swimming prey very effectively. They rely heavily on other senses, particularly smell, to detect and hunt prey.

Sharks and humans share many structural qualities when it comes to the eyes, so much so, that their corneas are sometimes used in cornea replacement surgery in humans.

Smelly feet

Although little research exists, it is believed that polar bears see about as well as humans, but they rely on their sense of smell to find prey and navigate their featureless environment.

One study showed that the feet of the polar bear have large sweat glands which could be used to mark a trail for other bears to follow.

A polar bear can smell a seal on the ice from 20 miles away or even buried in snow over a mile away.

It may seem surprising given their white–dominated landscape, but research suggests that polar bears have full colour vision, as well as good vision in low light conditions.

Best Night Vision

The owl has an abundance of light-sensitive rod cells at a density of 5 times greater than humans. In addition, the owl’s eyes are very large relative to the rest of its body. These factors allow the owl to have the best night vision in the animal kingdom.

Broadest Field of Vision

The chameleon’s ability to rotate each eye independently of each other allows it to see at nearly every angle without moving its head, allowing it to hunt without scaring off its prey.

Best Colour Vision

Unlike the human eye which has cones to allow it to perceive colour, the butterfly retina contains 6 or more photoreceptor classes with unique spectral capabilities. While much is still to be learned about the complex vision of the butterfly, it is believed that many of these photoreceptors are used to detect very specific types of colour stimuli.

Bug eyes

Insects have more eyes than humans. Butterflies have four eyes. Most spiders have eight eyes. Caterpillars have 12 eyes while houseflies have 4,000 lenses in each eye. A dragonfly’s eye contains about 30,000 lenses.

The insect compound eye is like having lots of little eyes looking in different directions, but each little eye doesn’t see very well.

The human eye can swivel, but it only looks in one direction at any given moment and the quality of its vision is much higher than that of a compound eye.

Most insects can only see light and dark, but a few, like bees, see more colours than humans, although they don’t have the additional qualities of vividness and shading.